Horace G. Jackson

High Resolution Computed Tomography of Positron Emitters

High resolution computed transaxial tomography has been performed on phantoms containing positron-emitting isotopes. The imaging system consisted of two opposing groups of eight NaI(T1) crystals 8 mm × 30 mm × 50 mm deep and the phantoms were rotated to measure coincident events along 8960 projection integrals as they would be measured by a 280 crystal ring system now under construction. The spatial resolution in the reconstructed images is 7.5 mm FWHM at the center of the ring and approximately 11 mm FWHM at a radius of 10 cm. We present measurements of imaging and background rates under various operating conditions. Based on these measurements, the full 280 crystal system will image 10,000 events per sec with 400 ¿Ci in a section 1 cm thick and 20 cm in diameter. We show that 1.5 million events are sufficient to reliably image 3.5 mm hot spots with 14 mm center-to-center spacing and isolated 9 mm diameter cold spots in phantoms 15-20 cm in diameter.

Nanosecond Pulse Amplifiers

Examples are given of the use of pulse amplifiers in three areas of experimental nuclear physics. The necessity of low noise at the input of these amplifiers leads to a discussion of electronic noise. The need for pulse-shaping networks in amplifiers particularly designed for accurate amplitude analysis is emphasized. The technique of using negative feedback to obtain nanosecond pulse amplifiers is discussed. Calculated and experimental results are given for two series-shunt feedback pair amplifiers. The necessity of using the hybrid fabrication technique in subnanosecond pulse amplifiers is shown as well as the characterization of the transistors and complete amplifier with the scattering (s) parameters. An annotated bibliography is included as an appendix.

Four‐Gun Oscilloscope for Use in Nuclear Research

>A unit was built around a four-gun cathode-ray tube which is quickly mounted to a Textronix Type 517 oscilloscope. The tube was a Dumont type W47gP11M having four independently deflected and focused beams. (W.D.M.)

A VERSATILE SCALER AND READ-OUT SYSTEM

Abstract A scaling system is described whose automatic readout can record from an unlimited number of scalers or other digital equipment. The readout system normally controls a paper-type punch at 60 characters per second or a typewriter at 15 characters per second, but magnetic-tape output has also been used. The scaler has a dead time per count of less than 100 nsec. Nixietube display is provided and a wide range of operating modes are possible. Planar silicon transistors and diodes are used exclusively in both the scaler and the read-out.

Beam-Profile Indicator

This paper describes an instrument for displaying intensity profiles of charged-particle beams that emerge from high-energy accelerators. The intensity vs position on a strip of 21 scintillation counters each 1 by 1 cm appears as a histogram on an oscilloscope. The display is accomplished by employing transistor circuits to amplify and integrate the outputs of the multiplier phototubes. The accumulated charge associated with each counter element is then read out in sequence by means of a blocking-oscillator commutator. The output signal is further amplified logarithmically for oscilloscope deflection.

Developments in Linear Integrated Circuits

The paper reviews recent developments of monolithic linear integrated circuits. Attention is given to operational amplifiers, voltage comparators and voltage regulators. Other developments including the monolithic four-quadrant analog multiplier and the phase-locked loop are also described.